This example shares the specific code displayed by ListView drop-down loading for your reference. The specific content is as follows
1、
public class MyListView extends ListView implements OnScrollListener {
private final static int RELEASE_To_REFRESH = 0;// The status value of the pull-down process private final static int PULL_To_REFRESH = 1; // Return from pull-down to the status value that does not refresh private final static int REFRESHING = 2;// The refreshing status value private final static int DONE = 3;
private final static int LOADING = 4;
// The ratio of the actual padding distance to the offset distance on the interface private final static int RATIO = 3;
private LayoutInflater inflater;
// The layout of refreshing the ListView head pull-down private LinearLayout headerView;
private TextView lvHeaderTipsTv;
private TextView lvHeaderLastUpdatedTv;
private ImageView lvHeaderArrowIv;
private ProgressBar lvHeaderProgressBar;
// Define the height of the layout for refreshing by the head pull-down private int headerContentHeight;
private RotateAnimation animation;
private RotateAnimation reverseAnimation;
private int startY;
private int state;
private boolean isBack;
// Used to ensure that the value of startY is recorded only once in a complete touch event private boolean isRecored;
private OnRefreshListener refreshListener;
private boolean isRefreshable;
public MyListView(Context context) {
super(context);
init(context);
}
public MyListView(Context context, AttributeSet attrs) {
super(context, attrs);
init(context);
}
private void init(Context context) {
inflater = (context);
headerView = (LinearLayout) (.lv_header, null);
lvHeaderTipsTv = (TextView) headerView
.findViewById();
lvHeaderLastUpdatedTv = (TextView) headerView
.findViewById();
lvHeaderArrowIv = (ImageView) headerView
.findViewById();
// Set the minimum height and width of the pull-down refresh icon (70);
(50);
lvHeaderProgressBar = (ProgressBar) headerView
.findViewById();
measureView(headerView);
headerContentHeight = ();
// Set the inner margin, just the height of the entire layout with a negative distance from the top, just hide the head (0, -1 * headerContentHeight, 0, 0);
// Repaint it ();
// Add the drop-down refreshed layout to the top of the ListView addHeaderView(headerView, null, false);
// Set scrolling listening events setOnScrollListener(this);
// Set rotation animation event animation = new RotateAnimation(0, -180,
RotateAnimation.RELATIVE_TO_SELF, 0.5f,
RotateAnimation.RELATIVE_TO_SELF, 0.5f);
(new LinearInterpolator());
(250);
(true);
reverseAnimation = new RotateAnimation(-180, 0,
RotateAnimation.RELATIVE_TO_SELF, 0.5f,
RotateAnimation.RELATIVE_TO_SELF, 0.5f);
(new LinearInterpolator());
(200);
(true);
// The initial state is the state where the pull-down refresh is completed, so it is DONE state = DONE;
// Is it refreshing? isRefreshable = false;
}
@Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
}
@Override
public void onScroll(AbsListView view, int firstVisibleItem,
int visibleItemCount, int totalItemCount) {
if (firstVisibleItem == 0) {
isRefreshable = true;
} else {
isRefreshable = false;
}
}
@Override
public boolean onTouchEvent(MotionEvent ev) {
if (isRefreshable) {
switch (()) {
case MotionEvent.ACTION_DOWN:
if (!isRecored) {
isRecored = true;
startY = (int) ();// Record the current position when the finger is pressed }
break;
case MotionEvent.ACTION_UP:
if (state != REFRESHING && state != LOADING) {
if (state == PULL_To_REFRESH) {
state = DONE;
changeHeaderViewByState();
}
if (state == RELEASE_To_REFRESH) {
state = REFRESHING;
changeHeaderViewByState();
onLvRefresh();
}
}
isRecored = false;
isBack = false;
break;
case MotionEvent.ACTION_MOVE:
int tempY = (int) ();
if (!isRecored) {
isRecored = true;
startY = tempY;
}
if (state != REFRESHING && isRecored && state != LOADING) {
// Ensure that the current position is always at the head during the padding process. Otherwise, if the list exceeds the screen, the list will scroll at the same time when pushing up. // You can let go and refresh if (state == RELEASE_To_REFRESH) {
setSelection(0);
// Push it up, pushing it to the point where the screen covers the head enough, but it has not yet been pushed to the point where it covers all if (((tempY - startY) / RATIO < headerContentHeight)// Change from release refresh state to pull-down refresh state && (tempY - startY) > 0) {
state = PULL_To_REFRESH;
changeHeaderViewByState();
}
// It was pushed to the top all at once else if (tempY - startY <= 0) {// Change from release refresh state to done state state = DONE;
changeHeaderViewByState();
}
}
// DONE or PULL_To_REFRESH status has not yet been reached when the display is released and refreshed if (state == PULL_To_REFRESH) {
setSelection(0);
// Pull down to the state where you can enter RELEASE_TO_REFRESH if ((tempY - startY) / RATIO >= headerContentHeight) {// Change from done or pull-down refresh status to release refresh state = RELEASE_To_REFRESH;
isBack = true;
changeHeaderViewByState();
}
// Push it to the top else if (tempY - startY <= 0) {// Change from DOne or pull-down refresh state to done state state = DONE;
changeHeaderViewByState();
}
}
// In done state if (state == DONE) {
if (tempY - startY > 0) {
state = PULL_To_REFRESH;
changeHeaderViewByState();
}
}
// Update the size of the headView if (state == PULL_To_REFRESH) {
(0, -1 * headerContentHeight
+ (tempY - startY) / RATIO, 0, 0);
}
// Update the paddingTop of headView if (state == RELEASE_To_REFRESH) {
(0, (tempY - startY) / RATIO
- headerContentHeight, 0, 0);
}
}
break;
default:
break;
}
}
return (ev);
}
// When the state changes, call this method to update the interface private void changeHeaderViewByState() {
switch (state) {
case RELEASE_To_REFRESH:
();
();
();
();
();// Clear animation (animation);// Start animation effect
("Release Refresh");
break;
case PULL_To_REFRESH:
();
();
();
();
();
// It is caused by the RELEASE_To_REFRESH state transition if (isBack) {
isBack = false;
();
(reverseAnimation);
("Drive down to refresh");
} else {
("Drive down to refresh");
}
break;
case REFRESHING:
(0, 0, 0, 0);
();
();
();
("Refreshing...");
();
break;
case DONE:
(0, -1 * headerContentHeight, 0, 0);
();
();
();
("Drive down to refresh");
();
break;
}
}
// This method is copied directly from a drop-down refresh demo on the network, here is the width and height of the headView. private void measureView(View child) {
params = ();
if (params == null) {
params = new (
.FILL_PARENT,
.WRAP_CONTENT);
}
int childWidthSpec = (0, 0 + 0,
);
int lpHeight = ;
int childHeightSpec;
if (lpHeight > 0) {
childHeightSpec = (lpHeight,
);
} else {
childHeightSpec = (0,
);
}
(childWidthSpec, childHeightSpec);
}
public void setonRefreshListener(OnRefreshListener refreshListener) {
= refreshListener;
isRefreshable = true;
}
public interface OnRefreshListener {
public void onRefresh();
}
public void onRefreshComplete() {
state = DONE;
("Latest Update:" + new Date().toLocaleString());
changeHeaderViewByState();
}
private void onLvRefresh() {
if (refreshListener != null) {
();
}
}
public void setAdapter(LvAdapter adapter) {
("Latest Update:" + new Date().toLocaleString());
(adapter);
}
}
2、
public class MainActivity extends Activity {
private List<String> list;
private MyListView lv;
private LvAdapter adapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
(savedInstanceState);
setContentView();
lv = (MyListView) findViewById();
list = new ArrayList<String>();
("loonggg");
("We are all developers");
("We are all developers");
("We are all developers");
("We are all developers");
("We are all developers");
("We are all developers");
("We are all developers");
("We are all developers");
("We are all developers");
("We are all developers");
("We are all developers");
("We are all developers");
("We are all developers");
("We are all developers");
("We are all developers");
("We are all developers");
adapter = new LvAdapter(list, this);
(adapter);
(new OnRefreshListener() {
@Override
public void onRefresh() {
new AsyncTask<Void, Void, Void>() {
protected Void doInBackground(Void... params) {
try {
(1000);
} catch (Exception e) {
();
}
("Refreshed content");
return null;
}
@Override
protected void onPostExecute(Void result) {
();
();
}
}.execute(null, null, null);
}
});
}
}
3、LvAdapter
public class LvAdapter extends BaseAdapter {
private List<String> list;
private Context context;
public LvAdapter(List<String> list, Context context) {
= list;
= context;
}
@Override
public int getCount() {
return ();
}
@Override
public Object getItem(int position) {
return (position);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
TextView tv = new TextView(());
((position));
return tv;
}
}
4、lv_header.xml
[html] view plain copy
<LinearLayout xmlns:androaa">/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:background="#000000" >
<!-- Content -->
<RelativeLayout
android:
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:paddingLeft="30dp" >
<!-- Arrow image, progress bar -->
<FrameLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_centerVertical="true" >
<!-- Arrow -->
<ImageView
android:
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:src="@drawable/arrow" />
<!-- Progress Bar -->
<ProgressBar
android:
style="?android:attr/progressBarStyleSmall"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:visibility="gone" />
</FrameLayout>
<!-- Tip, Latest Updates -->
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:gravity="center_horizontal"
android:orientation="vertical" >
<!-- Tip -->
<TextView
android:
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="drop-down refresh"
android:textColor="#fff"
android:textSize="20sp" />
<!-- Recently updated -->
<TextView
android:
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Last updated"
android:textColor="#333"
android:textSize="10sp" />
</LinearLayout>
</RelativeLayout>
</LinearLayout>
5、
[html] view plain copy
<LinearLayout xmlns:androaa">/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#000000"
android:orientation="vertical" >
<
android:
android:layout_width="fill_parent"
android:layout_height="fill_parent" />
</LinearLayout>
The above is all the content of this article. I hope it will be helpful to everyone's study and I hope everyone will support me more.